NEW YORK (Reuters Health) - The protease inhibitor BI201335 is a promising treatment constituent in patients with chronic hepatitis C virus (HCV) genotype-1 infection, researchers report in a November online paper in Hepatology.

The condition affects many millions worldwide, and as Dr. Michael P. Manns told Reuters Health by email, "BI201335 is a potent second-generation NS3/4A HCV protease inhibitor with once-daily dosing and a so far good safety profile, which is under promising further clinical development."

Dr. Manns of Hannover Medical School, Germany, and colleagues note that genotype-1 HCV is the most prevalent and difficult-to-treat HCV subtype. Standard care is with pegylated interferon alfa and ribavirin, but more than 50% of patients don't respond or relapse.

Inhibition of the NS3/NS4A HCV protease has been shown to suppress viral replication, and in the current study the researchers sought to assess the utility of BI201335 in this regard.

The team randomized 34 treatment-naive patients to monotherapy with placebo or BI201335 at 20 to 240 mg once-daily for 14 days. This was followed by 14 days of use along with pegylated interferon alfa/ribavirin.

Active monotherapy induced a rapid, dose-dependent decrease in plasma HCV RNA from baseline in all patients. Subsequently, viral load breakthrough was common. Addition of pegylated interferon alfa/ribavirin led to continuous viral load reductions in most patients.

A further 19 treatment-experienced patients also received combination treatment with 48 to 240 mg BI201335 for 28 days. Viral loads fell and breakthroughs were seen in only 3 of these patients.

In light of these and other findings, the researchers conclude that the data support "the investigation of different treatment regimens testing doses from 120 mg to 480 mg daily in phase IIb trials."